Proton-conducting membrane, method for their production and their use in electrochemical cells

A proton-conducting polymer membrane based on polyazoles, prepared by a process comprising the steps of

• A) mixing:
• one or more aromatic tetraamino compounds selected from the group consisting of 2,3,5,6-tetraaminopyridine, 3,3′,4,4′-tetraaminodiphenylsulfone, 3,3′,4,4′-tetraaminodiphenyl ether, 3,3′,4,4′-tetraaminobiphenyl, 1,2,4,5-tetraaminobenzene, 3,3′,4,4′-tetraaminobenzophenone, 3,3′,4,4′-tetraaminodiphenylmethane, 3,3′,4,4′-tetraaminodiphenyldimethyl-methane, and the salts of each thereof;
• and
• one or more aromatic carboxylic acids or esters thereof selected from the group consisting of-pyridine-2,5-dicarboxylic acid, pyridine-3,5-dicarboxylic acid, pyridine-2,6-dicarboxylic acid, pyridine-2,4-dicarboxylic acid, 4-phenyl-2,5-pyridinedicarboxylic acid, 3,5-pyrazoledicarboxylic acid, 2,6-pyrimidinedicarboxylic acid, 2,5-pyrazinedicarboxylic acid, 2,4,6-pyridinetricarboxylic acid, benzimidazole-5,6-dicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, 5-hydroxyisophthalic acid, 4-hydroxyisophthalic acid, -2-hydroxyterephthalic acid, 5-aminoisophthalic acid, 5-N,N-dimethylaminoisophthalic acid, 5-N,N-diethylaminoisophthalic acid, 2,5-dihydroxyterephthalic acid, 2,6-dihydroxyisophthalic acid, 4,6-dihydroxyisophthalic acid, 2,3-dihydroxyphthalic acid, 2,4-dihydroxyphthalic acid, 3,4-dihydroxyphthalic acid, 1,8-dihydroxynaphthalene-3,6-dicarboxylic acid,
• in polyphosphoric acid to form a solution and/or dispersion,
• B) heating the mixture from step A), and polymerizing until an intrinsic viscosity of at least 0.8 dl/g, to obtain polyazole polymer,
• C) forming a membrane using the polyazole polymer obtained in step B) on a carrier or on an electrode,
• D) optionally heating the membrane on the carrier or electrode,
• E) treating the membrane formed in step C) or D) in the presence of water or moisture, and
• F) removing the membrane from the carrier,
• wherein the total solid content of the polyazole polymer in the membrane is at least 10% by weight and up to about 25% by weight and said total content includes any acids, and water being present, but excludes any optional additives, the membrane has a Youngs modulus of at least 4.5 MPa.

An electrode with a proton-conducting polymer coating based on polyazoles, prepared by a process comprising the steps of

• A) mixing:
• one or more aromatic tetraamino compounds selected from the group consisting of 2,3,5,6-tetraaminopyridine, 3,3′,4,4′-tetraaminodiphenylsulfone, 3,3′,4,4′-tetraaminodiphenyl ether, 3,3′,4,4′-tetraaminobiphenyl, 1,2,4,5-tetraaminobenzene, 3,3′,4,4′-tetraaminobenzophenone, 3,3′,4,4′-tetraaminodiphenylmethane, 3,3′,4,4′-tetraaminodiphenyldimethyl-methane, and the salts of each thereof;
• and
• (ii) one or more aromatic carboxylic acids or esters thereof selected from the group consisting of pyridine-2,5-dicarboxylic acid, pyridine-3,5-dicarboxylic acid, pyridine-2,6-dicarboxylic acid, pyridine-2,4-dicarboxylic acid, 4-phenyl-2,5-pyridinedicarboxylic acid, 3,5-pyrazoledicarboxylic acid, 2,6-pyrimidinedicarboxylic acid, 2,5-pyrazinedicarboxylic acid, 2,4,6-pyridinetricarboxylic acid, benzimidazole-5,6-dicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, 5-hydroxyisophthalic acid, 4-hydroxyisophthalic acid, 2-hydroxyterephthalic acid, 5-aminoisophthalic acid, 5-N,N-dimethylaminoisophthalic acid, 5-N,N-diethylaminoisophthalic acid, 2,5-dihydroxyterephthalic acid, 2,6-dihydroxyisophthalic acid, 4,6-dihydroxyisophthalic acid, 2,3-dihydroxyphthalic acid, 2,4-dihydroxyphthalic acid, 3,4-dihydroxyphthalic acid, 1,8-dihydroxynaphthalene-3,6-dicarboxylic acid, or
• (iii) one or more aromatic and/or heteroaromatic diaminocarboxylic acids, in polyphosphoric acid to form a solution and/or dispersion,
• B) heating the mixture from step A), and polymerizing until an intrinsic viscosity of at least 0.8 dl/g, to obtain a polyazole polymer,
• C) applying a layer using the polyazole polymer obtained in step B) on an electrode,
• D) optionally heating the layer on the electrode, and
• E) treating the layer formed in step C) or D) in the presence of water or moisture to form a membrane on the electrode,
• wherein the total content of all polyazole polymers in the membrane is at least 10% by weight and up to about 25% by weight and said total content includes any acids, and water being present, but excludes any optional additives, the membrane has a Youngs modulus of at least 4.5 MPa.

A proton-conducting polymer membrane based on polyazoles, prepared by a process comprising the steps of

• A) mixing:
• one or more aromatic tetraamino compounds, and one or more aromatic carboxylic acids selected from the group consisting of pyridine-2,5-dicarboxylic acid, pyridine-3,5-dicarboxylic acid, pyridine-2,6-dicarboxylic acid, pyridine-2,4-dicarboxylic acid, 5-hydroxyisophthalic acid, 4-hydroxyisophthalic acid, 2-hydroxyterephthalic acid, 2,5-dihydroxyterephthalic acid, 2,6-dihydroxyisophthalic acid, 4,6-dihydroxyisophthalic acid, 2,3-dihydroxyphthalic acid, 2,4-dihydroxyphthalic acid, 3,4-dihydroxyphthalic acid, 1,8-dihydroxynaphthalene-3,6-dicarboxylic acid, diphenylsulfone-4,4′-dicarboxylic acid, and any one ester of each dicarboxylic acid thereof,
• in polyphosphoric acid to form a solution and/or dispersion;
• B) heating the mixture from step A), and polymerizing until an intrinsic viscosity of at least 0.8 dl/g, to obtain polyazole polymer;
• C) forming a membrane using the polyazole polymer obtained in step B) on a carrier or on an electrode;
• D) optionally heating the membrane on the carrier or electrode;
• E) treating the membrane formed in step C) or D) in the presence of water or moisture;
• and
• F) removing the membrane from the carrier;
• wherein the total solid content of the polyazole polymer in the membrane is at least 10% by weight and up to about 25% by weight and said total content includes any acids, and water being present, but excludes any optional additives, the membrane has a Youngs modulus of at least 4.5 MPa.